Kel, I just read your post again and you know what, it's not your son that needs to be talked to, it's the grandparents! They really do need to support you by telling him that it's not nice to say things like that and to behave when you come to get him. You can't expect a four year old to understand very well about hurt feelings. All he knows is he has a great time and gets to do whatever he likes. Heck, us adults wouldn't mind having somewhere like that to go to sometimes too!
I hate to say it, but are you absolutely sure they're not encouraging it? I knew a lady who spent all her time when her estranged granddaughter visited saying 'Would you like to come live at Grandma's house all the time? We could have such fun! Do you like living with mommy? You could sleep in such and such a room, we could do this and that (
which of course was things mommy never had time to do with her) " etc etc.
So by the time the kid was getting picked up, in her small mind she'd practically moved in and just needed the one obstacle that stopped her from doing so to be removed- her mother. She of course thought if she yelled enough eventually someone would say " okay, just stay then!" The grandma always pleaded ignorance as to why the little one was behaving like that of course but I saw it with my own eyes many times and quite frankly it made me sick.
Small kids always say yes they'd like to live there because Grandma's is the fun place. We parents just have the day to day responsibility of dealing with everything else! Don't take it to heart or allow it to hurt you. Just pick him up and take him out, tucked under your arm if necessary lol. When you get home, no treats or anything, just put him in his room.
He needs to know that it's unacceptable to throw a tantrum then expect to get away with it. Since he's doing it as a habit now, that habit needs to be broken sooner rather than later because the more he gets away with it, the more he'll do it. Before you know it you'll be chasing him around MacDonalds with him screeching at you. If you think it happening in the relative privacy of someone's home is bad, try that for size!
Timeouts etc only work if you're consistent. If you keep doing it week after week, he'll soon get the message that it's not going to stop until he does. A pain to do, I know, but it works. Best of luck, you're doing the hardest job in the world but you're not alone. Keep your chin up.
